Breathing training improves exercise capacity in patients with tetralogy of Fallot: A randomised trial

Objective Patients with tetralogy of Fallot (ToF) have limited pulmonary blood flow before corrective surgery and ongoing dysfunction of the pulmonary valve and right ventricle throughout life leading to lower exercise capacity and lung volumes in many patients. Inhalation training can increase lung volumes, improve pulmonary blood flow and consequently exercise capacity. This study tests whether home-based daily breathing training improves exercise capacity and lung volumes. Methods From February 2017 to November 2018, 60 patients (14.7±4.8 years, 39% female) underwent spirometry (forced vital capacity (FVC); forced expiratory volume in 1 s (FEV 1)), cardiopulmonary exercise testing (peak oxygen uptake (peak V˙ O 2)) and breathing excursion measurement. They were randomised into immediate breathing exercise or control group (CG) and re-examined after 6 months. The CG started their training afterwards and were re-examined after further 6 months. Patients trained with an inspiratory volume-oriented breathing device and were encouraged to exercise daily. The primary endpoint of this study was the change in peak V˙ O 2. Results are expressed as mean±SEM (multiple imputations). Results In the first 6 months (intention to treat analysis), the training group showed a more favourable change in peak V˙ O 2 ( "0.5±0.6 vs -2.3±0.9 mL/min/kg, p=0.011), FVC ( "0.18±0.03 vs 0.08±0.03 L, p=0.036) and FEV 1 ( "0.14±0.03 vs -0.00±0.04 L, p=0.007). Including the delayed training data from the CG (n=54), this change in peak V˙ O 2 correlated with self-reported weekly training days (r=0.282, p=0.039). Conclusions Daily inspiratory volume-oriented breathing training increases dynamic lung volumes and slows down deconditioning in peak V˙ O 2 in young patients with repaired ToF.